Since you are using Sigil
You use the 'place image tool' (black screen icon) to place the code for any image in the (image section) list
You can use the same image (file) as many times as you can click

. Common repeated use: fleurons used as scene breakers or chapter head decorations
Again: the file name is solely for YOU, the book designer.
You can use lame names

: pic01,pic02...
or meaningful descriptive names like shown in Turtle91's post
The book does not care